Method of annealing articles.



A. L. POLLARD.

METHOD OF ANNEALING ARTICLES.

APPLICATION FILED DEC-1| 1916.

1,222,?93, Patented Apr. 17, 1917.

l VENTDFE 7 /6 by Z9414 ATT DRNEY.

ARTHUR L. POLLARD, OF BATAVIA, NEW YORK.

METHOD OF ANNEALING ARTICLES.

Application filed December 1, 1916.

To all whom it may concern:

Be it known that l, ARTHUR L. POLLARD, a citizen of the Unitec States,residing at Batavia, in the county of Genesee and State of New York,have invented new and useful Improvements in Methods of AnnealingArticles, of which the following is a specification.

This invention relates to a method of annealing castings of iron orsimilar material so as to render the same soft or malleable.

lileretofore annealing of castings has generally been effected either byplacing the articles to be annealed in a pot of iron or steel arrangedin an oven with or without the addition thereto of a protective oractive material such as slag or mill scale, or the castings were chargedloosely into a muflie oven together with a suitable protecting materialafter which the oven is heated a suflicient length of time to thoroughlyheat the castings under treatment and then the heat is shut off and theca stings are allowed 'to cool slowly. The use of such pots involvesconsiderable expense and the heating of the castings therein as well asthe heating of castings when charged loosely into a mufile ovennecessitated the placing the pots filled with casting in the oven orcharging the loose castings and protecting material in the oven whilethe heat was practically cut off from the same, and as the entire masswas usually very thick an undue length of time was required forthoroughly heating the castings, it being necessary in most instances toheat the same from about two days to about a week in orderto accomplishthis purpose. This necessarily involved undue loss of time and increasedthe cost of the product accordingly.

It is the object of this invention to provide a method of annealingcastings or other articles of this character whereby the time in whichthe heating of the castings is very materially reduced and acorresponding reduction in the cost of annealing the same is efiected;

ln carrying out this improved process the heating 01 the casting orsimilar articles along with the protective material is effected bycharging the castings into the oven together with a comparatively thinlayer of protecting material over the same while the furnace is underfire or being heated. Inasmuch as the castings at this time areseparated from the heating agent by a thin layer Specification ofLetters Patent.

Patented Apr. 17, 191%.

Serial No. 134,290.

of protecting material the heat is able to penetrate this protectingmaterial and reach the castings and heat them to the proper eX- tent ina comparatively short time suitable for rendering the same soft ormalleable. In most cases the time required for heating the castingswhile protected by a thin layer of mill scale, slag or similar materialis about two hours. After this the'heating agent is cut off and the ovenis permitted to cool down slowly in the usual manner being usually fromabout two days to about one Week depending upon the character and sizeof the castings which are being annealed.

When a large quantity of castings is to be annealed in accordance withmy improved process the castings and protecting material are charged inalternate layers into the even while the same is under heat, theselayers being superposed, and the heating of each layer of castings witha covering of pro tecting material above the same being continued for asu'llicient length of time to thoroughly anneal the respective layer ofcastings before another layer of unannealed castings together with aprotecting covering of mill scale or slag is charged into the oven.These successive layers of castings and protecting material are chargedalternately into the oven until the latter is filled and then theheating of the entire mass is continued until the uppermost layer ofcastings has been sufiiciently heated to render the same soft ormalleable. Each of the several layers of castings is in this mannerheated very quickly inasmuch as the same at the time of heating is onlyseparated from the heat of the oven by a thin layer of protectingmaterial. Each layer of castings therefore requires only about two hoursof heat treatment in order to render the same soft or malleable, therebyenabling the time for heating a large number of superposed andalternating layers of castings and protecting material to be reducedconsiderably as compared with a process in which a large andcomparatively thick mass of castings and protecting material is heatedat one time, inasmuch as the heating of such a large mass must becontinued for a much longer period of time in order to enable the heatto penetrate the mass and reach and properly heat the castings in theinnermost part of the same.

After the layers of castings and protecting covering have beensuccessively charged into the oven while the latter is under heat andthe last batch or layer of such castings has been heated the requiredextent, the heat supplied to the furnace is shut down and the castingsare allowed to cool slowly and for a sufficient length of time to retainthe malleability in the castings.

The oven by which my improved method of annealing castings or similarmaterials is effected may be variously constructed but that shown in theaccompanying drawings is typical of one form which is suitable for thispurpose.

In these drawings:

Figure 1 is a horizontal section taken on line 11, Fig: 3 showing oneform of annealingoven whereby my improved method may be practised. Fig.2 is a vertical longitudinal section of the same taken on line 2-2, Fig.3. Fig. 3 is a vertical transverse section taken on line 33, Fig. 2.

In the following description similar characters of reference refer tolike parts in the several figures.

1 represents the foundation of the oven, 2, 2 the upright longitudinalside walls thereof, 3, 4- the front and rear end walls thereof, 5 theroof connecting the side and end walls at the top thereof and 6 a firewall or bridge extending transversely across the interior of the oven ata distance rearvmrdly from the front wall and dividing the interior ofthe oven into a front furnace or heater 7 and a rear charging orannealing chamber 8 which receives the castings to be annealed and theprotecting material for covering the castings.

The heat may be generated in any suitable manner, for instance by agrate 9 upon which hard fuel. is placed through a feed opening 10 in thefront wall, the ashes of the fuel being removed through a deliveryopening 11 formed in the front wall below the grate. It is to beunderstood, however, that any other suitable heating means, agent ormedium may e employed instead of burning hard fuel over the grate. Thetop of the partition 6 is separated from the roof of the oven by a heatpassage 12 connecting the furnace with the annealing or chargingchamber.

Within the charging or annealing chamber and arranged at a distance fromthe side walls of the oven are two upright longitudinal partitions 13,13 which extend from the foundation of the oven upwardly to within ashort distance of the roof so as to form longitudinal heat passages 11between the longitudinal walls of the oven and the longitudinalpartitions 13 which passages 1 1 communicate at their upper ends withthe top of the charging space between the longitudinal partitions, asclearly shown in Fig. 3.

At different points in the height of the longitudinal walls the same areprovided with heat openings or conduits 15 so that the heat can passfreely through these openings when the same are not obstructed byprotecting material. The undersides of these heating openings arepreferably inclined downwardly toward the center of the oven, so thatthere is little, if any, tendency for protecting ma erial to lodge inthe same.

16, 16 represent the main pipes "of two ex haust flues which arearranged lengthwise and horizontally in the foundation beneath the ovenand which have their outlet ends connected with a chimney or other meansfor exhausting the heated air from these lines while their inlet endsare connected respectively by ineansof a plurality of branch pipes orpassages 17 with the lower parts of the longitudinal heat passages 1-1,each of these branch pipes being preferably formed partly in thefoundation and partly in the lower ends of the longitudinal oven walls,as shown in Fig. 3. The escape of the heating medium from the mainexhaust pipes may be regulated or shut off altogether by means of aclosure which in the present instance consists of a vertically movablevalve, slide or shutter 18 which is adapted to be moved into and out ofa position across the outlet portion of each main flue and which isaccessible from above the foundation so that the same may bemanipulated. The castings and protecting materials are charged into thecharging space of the oven through one or more charging or feed openings19 ar- 100 ranged in the roof of the oven above the charging space, fourof such openings being shown in the drawings and each adapted to becovered by means of a lid 20 when the rcspective opening is not in use.

In operating this oven for annealing iron castings or similar materialsor articles in accordance with my intention the furnace is fired and thedampers or shutters 18 are opened so as to cause the heat to pass fromthe furnace rearwardly into the charging space or annealing chamber andthe longitudinal passages 1 1 and transverse openings 15 connecting thesame and thence through the branch and main pipes of the exhaust finesto the chimney or other exhausting device leading to the outeratmosphere. After the oven has been heated to the required extent alowermost layer 21 of protecting material such as slag or mill scale isplaced upon the floor or bottom of the charging chamber, then a layer orbatch 22 of castings is placed over the lowermost layer of protectingmaterial and then these castings are covered by a comparatively thinlayer 23 of protecting material such as slag or mill scale. The chargingof this layer of castings with the protecting material into the oven iseffected through the openings 19 While the oven is under heat and afterthis charging operation has been completed the lids 20 are placed overthe filling openings and the furnace is operated under heat for asuiiicient length of time to properly heat the layer of castings whichhas just been introduced into the oven, the time required for thispurpose being approximately two hours although this varies according tothe particular character or size of the castings which are beingtreated. After one layer of castings has been heated in the mannerdescribed another layer 24 of castings is in like manner charged intothe annealing chamber of the oven together with a covering 25 ofprotecting material while the oven is under heat and then the chargingis suspended and the heating of the furnace continued until the lastmentioned layer of castings has been softened or rendered malleable,this operation likewise being effected in a comparatively short time byreason of only a thin layer, of protecting material being interposedbetween the last mentioned layer of castings and the heating agent. Thisoperation is repeated for each successive layer of castings which isintroduced into the annealing chamber and covered by a thin layer ofprotecting material until the annealing chamber has been filled to thetop. When the uppermost layer of castings has been heated sufficientlyin the manner described the heat is shut off and the dampers 18 areclosed so as to prevent further heating of the castings and then theentire mass of castings and protecting material in the annealing chamberis allowed to cool slowly the required length of time to preserve themalleability of the castings. After the castings have been suilicientlycooled the same are removed together with the protecting material fromthe annealing chamber, this removal being preferably effected throughthe rear end of the charging chamber by first taking down or removingthe rear end wall 4 or so much thereof as may be necessary to accomplishthis purpose. After the castings and protecting material have beenremoved from the charging chamber this rear wall is agaln restoredpreparatory to annealing another lot of castings when the operation isrepeated as before described.

My improved process for annealing iron castings or similar material forrendering the same malleable effects a large saving in the cost ofproducing such articles by reason of the fact that the oven is capableof yielding a larger output within a given length of time than has beenpossible heretofore. Furthermore, it permits of employing the attendantsof the annealing furnace to greater advantage by reason of a reductionin the length of the intervals of rest which have been necessary in themethods of annealing heretofore used.

Moreover this process dispenses with the use of pots and the expenseincident thereto.

I claim as my invention:

The herein described method of annealing articles which comprisesplacing a layer of articles to be annealed in an oven and covering saidlayer of articles with a layer of protecting material in the presence ofa heating medium and then suspending the further addition of articlesand protecting material until said articles have been heatedsufficiently to render them malleable, then successively adding anotherlayer of articles to be annealed and another layer of protectingmaterial in the presence of a heating medium and continuing the heatingof the same until the last layer of articles has been heatedsufiiciently to render them malleable, and then in like mannersuccessively adding further layers of articles to be annealed and layersof protecting material in the presence of a heating medium until theoven has been filled to the required extent and continuing theapplication of heat thereto until the last layer of articles has beenheated sufficiently to render them malleable, and then permitting thewhole mass of articles and protect ing material to cool slowly.

ARTHUR L. POLLARI).

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). C.

